As is known in the art, the design of a mechanical product or device is generally an iterative, multi-level decision-making engineering process, where the highest level functional requirements (FRs) are decomposed in a systematic manner. The design process typically begins with an identification of customer needs and proceeds through a sequence of activities to seek a solution to the defined task through specification, synthesis, analysis, and evaluation. The process ends with the detailed description and/or geometric models of the product.
The design process can be divided into three stages. A first stage corresponds to a mapping from customer needs to FRs, where information about a product is collected and transformed into engineering specifications and goals. A second stage corresponds to a conceptual design phase, in which the primary concern is the generation of geometric designs to meet the FRs through the creation of design alternatives and selection of a best design from the set. Designers at this stage must create rough sketches or solid models and pass them along to other designers with descriptions of the concepts in order to detail the concepts. A third stage corresponds to a detailed design phase. During this final phase, final decisions about dimensions are made. Also, more detailed geometric shapes of individual components are generated. Furthermore, material selections are made. Among the three stages described above, the conceptual design phase plays an important role in the overall success of design. Good design decisions made during the conceptual design phase can reduce iterations between design stages and processes, and eventually lead to a satisfactory final product.
Current computer aided design (CAD) technology successfully supports generation of geometric shapes and assemblies of physical objects in the detailed design stage using solid modeling techniques and specific data structures. However, current CAD programs are understood as drawing packages, which cannot be used to support the conceptual design stage described above. Solid modeling techniques are useful only after detailed shapes of the physical objects have been determined.
There exist many CAD approaches to using a database in the design process. Many of these approaches classify CAD models by similarity of shapes. Thus, the design process involves receiving an input geometric model, and searching the database for a shape similar to the geometric model. In these approaches, it is relatively easy to collect and classify CAD models and to find similar shapes from a CAD database, but still the CAD database cannot help designers generate design solutions. The conventional CAD database is usually used merely to find similar parts for manufacturing purpose and to classify shapes.
The organization of design information is an important factor in determining performance and functionality of a CAD system. Existing CAD systems are primarily concerned with data structure and information flow for representing and constructing 3D shapes. The existing CAD systems enable generation of complex shapes. They also utilize the geometric information in designing and manufacturing products. Feature-based representation or design is a result of such an effort. One of the key benefits of using features is that the designer can put their design intent into the geometric model. Also, many techniques using features have been developed to automate machining, to diagnose the defect of geometric models, to generate finite element models, and so on.